The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing systems may be used to perform etching and/or other treatment of substrates such as semiconductor wafers. A substrate may be arranged on a pedestal in a processing chamber of the substrate processing system. For example during etching in a plasma enhanced chemical vapor deposition (PECVD) process, a gas mixture including one or more precursors is introduced into the processing chamber and plasma is struck to etch the substrate.
Edge coupling rings have been used to adjust an etch rate and/or etch profile of the plasma near a radially outer edge of the substrate. The edge coupling ring is typically located on the pedestal around the radially outer edge of the substrate. Process conditions at the radially outer edge of the substrate can be modified by changing a position of the edge coupling ring, a shape or profile of an inner edge of the edge coupling ring, a height of the edge coupling ring relative to an upper surface of the substrate, a material of the edge coupling ring, etc.
Changing the edge coupling ring requires the processing chamber to be opened, which is undesirable. In other words, an edge coupling effect of the edge coupling ring cannot be altered without opening the processing chamber. When the edge coupling ring is eroded by plasma during etching, the edge coupling effect changes. Correcting erosion of the edge coupling ring requires the processing chamber to be opened in order to replace the edge coupling ring.
Referring now to FIGS. 1-2, a substrate processing system may include a pedestal 20 and an edge coupling ring 30. The edge coupling ring 30 may include a single piece or two or more portions. In the example in FIGS. 1-2, the edge coupling ring 30 includes a first annular portion 32 arranged near a radially outer edge of a substrate 33. A second annular portion 34 is located radially inwardly from the first annular portion below the substrate 33. A third annular portion 36 is arranged below the first annular portion 32. During use, plasma 42 is directed at the substrate 33 to etch the exposed portions of the substrate 33. The edge coupling ring 30 is arranged to help shape the plasma such that uniform etching of the substrate 33 occurs.
In FIG. 2, after the edge coupling ring 30 has been used, an upper surface of a radially inner portion of the edge coupling ring 30 may exhibit erosion as identified at 48. As a result, plasma 42 may tend to etch a radially outer edge of the substrate 33 at a faster rate than etching of radially inner portions thereof as can be seen at 44.